It's kinda obvious (and it's earlier) but....
In July 1986, after being on hiatus for three years or so, The Police get together to record their follow-up to Synchronicity. Unfortunately, around this time, drummer Stuart Copeland falls from a horse during a polo match (so rock and roll!) and breaks his collar bone. Unable to play, he and Sting reportedly spend a couple of weeks arguing about which drum machine to use and the sessions end fruitlessly.
So, in the new timeline, Copeland is able to play. More importantly, the band manages to jell again and not (...as would be most likely...) fall to squabbling about something else. Sting gives the band the songs he would have used on his second solo album in 1987. The album is a smash success and after the tour to support it, the window of opportunity for Sting to become a smash solo artist closes.
Humbled, the former school teacher decides that being a regular old multi-millionaire isn't so bad, grits his teeth and manages to spend the rest of his career with the band. In doing so, the spot R.E.M. would have taken is blocked and they become one of those bands - like The Replacements or The Pixies - who achieve critical success but never quite break out.